Visual impairment is common in patients with major depressive disorder. The visual processing ability of patients with depression is impaired at all stages. Current studies focus on contrast sensitivity， visual masking， visual attention， facial expression recognition， visual motion. Visual processing disorders can lead to the deficit of normal sensory perception， so that the reward pathway cannot be activated properly， and then aggravate the anhedonia in patients with depression. This article reviews the impairment of visual processing in major depressive disorder and the related brain mechanisms， so as to provide reference for further research.